Copper-aluminum electrical joint

ABSTRACT

A circuit breaker, or transformer, or insulated bus for use with AC voltages greater than 30 kilovolts and AC currents greater than 400 amperes includes an elongated bushing made from electrically insulating material and having first and second ends. The first end of the bushing is coupled to a main enclosure of the circuit breaker, or transformer, or insulated bus and a terminal pad is coupled to the second end of the bushing. A conductor is disposed in an internal cavity of the bushing in spaced relation to an internal wall of the bushing that defines the internal cavity. The conductor includes first and second segments. A first end of the first segment is electrically connected to a contact of the circuit breaker, or transformer, or insulated bus and a first end of the second segment is electrically connected to the terminal pad. Second ends of the first and second segments are coupled together with a biasing element interposed between the second ends of the first and second segments. The biasing element is operative for biasing the first end of the first segment toward the contact and for biasing the first end of the second segment toward the one terminal pad.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to circuit breakers utilized with ACvoltages greater than 30 kilovolts and AC currents greater than 400amperes and, more specifically, to dissipating heat associated with theoperation of said circuit breakers and for improving the reliability ofelectrical connections of multi-segment conductors disposed insidebushings of the circuit breakers.

2. Description of Related Art

An exemplary three-phase, mechanically ganged, sulfur hexafluoride (SF₆)gas insulating circuit breaker system includes a plurality of circuitbreakers. Each circuit breaker includes a main enclosure which houses aninterrupter Each circuit breaker also includes a pair of insulatingbushings having first ends coupled to the main enclosure and havingsecond ends coupled to line terminals.

As electrical current flows through such circuit breaker, thetemperature of the enclosed gas increases due to the heat generated fromthe resistivity of the conductive parts. The warm gas tends to rise andstagnate at the highest point, which is usually just below the lineterminals at the tops of the bushings.

It would be desirable to provide a means that facilitates the removal ofheat from the warm gas at the top of the bushings.

SUMMARY OF THE INVENTION

Disclosed herein is a circuit breaker for use with AC voltages greaterthan 30 kilovolts and AC currents greater than 400 amperes. The circuitbreaker comprises: a main enclosure housing an interrupter that iselectrically insulated from the main enclosure, wherein the interrupteris switchable between a closed state where first and second contacts ofthe interrupter are electrically connected defining a conductive pathfor current to flow between the first and second contacts and an openstate where the first and second contacts of the interrupter areelectrically isolated from each other, and vice versa; first and secondelectrically insulating bushings having proximal ends coupled to themain enclosure; first and second conductors disposed inside of the firstand second bushings, wherein proximal ends of the first and secondconductors are electrically connected to the first and second contactsof the interrupter defining a conductive path for current to flowbetween the first and second contacts and the first and secondconductors, respectively; first and second terminal pads coupled betweendistal ends of the first and second bushings and distal ends of thefirst and second conductors disposed inside of the first and secondbushings, respectively; and first and second extruded radiators coupledbetween the distal ends of the first and second bushings and the firstand second terminal pads, respectively, wherein portions of the firstand second conductors are disposed inside of the first and secondextruded radiators.

The inside of each bushing can include a cavity defined by an interiorwall of the bushing. Each conductor can be disposed in the cavity of oneof the bushings in spaced relation to the interior wall of the bushing.

The interrupter and the first and second conductors can be exposed to anelectrically insulating gas that is disposed in the main enclosure andthe insides of the bushings and the extruded radiators.

The inside of each extruded radiator can include includes a cavitydefined by an interior wall of the extruded radiator that is in spacedrelation with the portion of one of the first and second conductors.

An outside (or exterior) of each extruded radiator can include one ormore fins.

A subset of the fins (i.e., all or a portion of the fins) of eachextruded radiator can include internally threaded holes that areconfigured to mate with externally threaded bolts to couple the extrudedradiator to the distal end of one of the bushings, to one of theterminal pads, or to both.

A distal end of the one of the bushings can include includes a flangeadjacent the bushing's distal end. The externally threaded bolts cancouple the extruded radiator to the distal end of the one bushing viathe flange.

Each extruded radiator can be coupled to either the distal end of one ofthe bushings or to one of the terminal pads via an interface plate thatis coupled to the extruded radiator.

The interface plate can be coupled to the extruded radiator via welding.

Each extruded radiator can be coupled to first and second interfaceplates. The first interface plate of each extruded radiator can also becoupled to the distal end of one of the bushings. The second interfaceplate of each extruded radiator can also be coupled to one of theterminal pads.

The first interface plate can be coupled to the distal of the saidbushing via a flange disposed adjacent the bushing's distal end.

The first and second interface plates can be coupled to the distal endof the bushing and the terminal pad, respectively, via externallythreaded bolts mating with one or more patterns of internally threadedholes in the extruded radiator.

Each interface plate can be coupled to the extruded radiator viawelding.

Each extruded radiator can be formed from aluminum.

Also disclosed herein is a circuit breaker, or transformer, or insulatedbus for use with AC voltages greater than 30 kilovolts and AC currentsgreater than 400 amperes. The circuit breaker, or transformer, orinsulated bus comprises: an elongated bushing made from electricallyinsulating material and having first and second ends, the first end ofthe bushing adapted to be coupled to a main enclosure; an elongatedextruded radiator having first and second ends, wherein the first end ofthe extruded radiator is coupled to the second end of the bushing; aterminal pad coupled to the second end of the extruded radiator; and aconductor disposed in internal cavities of the bushing and the extrudedradiator in spaced relation to internal walls of the bushing and theextruded radiator that define the internal cavities, wherein one end ofthe conductor is electrically connected to the terminal pad.

The extruded radiator can include one or more fins. A subset of the fins(i.e., all or a portion of the fins) can include internally threadedholes that are configured to mate with externally threaded bolts tocouple the extruded radiator to the second end of bushing, to theterminal pad, or to both.

A first interface plate can be coupled between the first end of theextruded radiator and the second end of the bushing. A second interfaceplate can be coupled between the terminal pad and the second end of theextruded radiator.

The extruded radiator and the first and second interface plates can becoupled together to form a singular, unified piece.

Threaded bolts can be used to couple the second end of the bushing andthe terminal pad to the respective first and second interface plates.

Adjacent the second end of the bushing a flange can be provided that isused to couple the first end of the extruded radiator to the second endof the bushing.

Also disclosed herein is a circuit breaker for use with AC voltagesgreater than 30 kilovolts and AC currents greater than 400 amperes. Thecircuit breaker comprises: a main enclosure housing an interrupter thatis electrically insulated from the main enclosure, wherein theinterrupter is switchable between a closed state where first and secondcontacts of the interrupter are electrically connected defining aconductive path for current to flow between the first and secondcontacts and an open state where the first and second contacts of theinterrupter are electrically isolated from each other, and vice versa;first and second electrically insulating bushings having proximal endscoupled to the main enclosure; first and second conductors disposedinside of the first and second bushings, wherein proximal ends of thefirst and second conductors are electrically connected to the first andsecond contacts of the interrupter defining a conductive path forcurrent to flow between the first and second contacts and the first andsecond conductors, respectively; and first and second terminal padscoupled between distal ends of the first and second bushings and distalends of the first and second conductors disposed inside of the first andsecond bushings, respectively, wherein: at least one conductor includesfirst and second segments; a first end of the first segment iselectrically connected to one of the contacts of the interrupter; afirst end of the second segment is electrically connected to one of theterminal pads; a second end of the first segment is coupled to a secondend of the second segment; and a biasing element is interposed betweenthe second ends of the first and second segments, wherein the biasingelement is operative for biasing the first end of the first segmenttoward the contact of the interrupter and for biasing the first end ofthe second segment toward the one terminal pad.

First and second radiators can be coupled between the distal ends of thefirst and second bushings and the first and second terminal pads,respectively. At least a portion of the first or second segment of theone conductor can be disposed inside one of radiators

The second ends of the first and second segments can be coupled togethervia male threads of one segment threadedly engaged in female threads ofthe other segment.

One segment can be made from aluminum. The other segment can be madefrom copper. At least one of the male threads and the female threads canbe coated with a conductive plating, e.g., silver, copper, or tinplated.

The first end of the first segment can be coupled directly to thecontact of the interrupter. The first end of the second segment can becoupled directly to the one terminal pad.

The biasing element can include a Belleville washer (also known as aconed-disc spring, a conical spring washer, a disc spring, a Bellevillespring, a frustoconical spring washer, or a cupped spring washer) or acoiled spring.

The biasing element can include a pair of Belleville washers connectedin series or in parallel.

At least one conductor can further include a third segment coupled withthe first segment, with the second segment, or with both of the firstand second segments.

Lastly, disclosed herein is a circuit breaker, or transformer, orinsulated bus for use with AC voltages greater than 30 kilovolts and ACcurrents greater than 400 amperes. The circuit breaker, or transformer,or insulated bus comprises: an elongated bushing made from electricallyinsulating material and having first and second ends, the first end ofthe bushing coupled to a main enclosure; a terminal pad coupled to thesecond end of the bushing; and a conductor disposed in an internalcavity of the bushing in spaced relation to an internal wall of thebushing that defines the internal cavity, wherein: the conductorincludes first and second segments; a first end of the first segment iselectrically connected to a contact; a first end of the second segmentis electrically connected to the terminal pad; a second end of the firstsegment is coupled to a second end of the second segment; and a biasingelement is interposed between the second ends of the first and secondsegments, wherein the biasing element is operative for biasing the firstend of the first segment toward the contact and for biasing the firstend of the second segment toward the terminal pad.

An elongated radiator can be disposed between the second end of thebushing and the terminal pad. At least a portion of the first or secondsegment of the conductor can be disposed inside of the radiator.

The second ends of the first and second segments can be coupled togethervia male threads of one segment threadedly engaged in female threads ofthe other segment.

One segment can be made from aluminum. The other segment can be madefrom copper. At least one of the male threads and the female threads canbe coated with a conductive plating, e.g., silver, copper, or tinplated.

The first end of the first segment can be coupled directly to thecontact. The first end of the second segment can be coupled directly tothe one terminal pad.

The biasing element can include a Belleville washer (also known as aconed-disc spring, a conical spring washer, a disc spring, a Bellevillespring, a frustoconical spring washer, or a cupped spring washer) or acoiled spring.

The biasing element can include a pair of Belleville washers connectedin series or in parallel.

The conductor can further include a third segment coupled with the firstsegment, with the second segment, or with both of the first and secondsegments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isolated perspective view of a conventional circuit breakersystem including three circuit breakers, each of which can be connectedto a single phase of a three phase AC distribution system;

FIGS. 2A and 2B are cross-sectional views of one of the circuit breakersshown in FIG. 1 with the interrupter of the circuit breaker in closedand open states, respectively;

FIG. 3A is a cross-sectional plan view of an instance of a currentsolution radiator that can be coupled between the distal end of one ofthe bushings and a terminal pad of the circuit breakers shown in FIGS.2A and 2B;

FIG. 3B is an enlarged isolated view of the connection of a single finto the exterior of the tube portion of the radiator shown in FIG. 3A;

FIG. 3C is a section taken along lines IIIC-IIIC in FIG. 3A;

FIG. 4A is a section of an extruded radiator of a first embodimentradiator taken along lines IVA-IVA in FIG. 4C;

FIG. 4B is a section of the circuit breaker shown in FIG. 2A includingbetween each bushing and each terminal pad a cross-section of the firstembodiment radiator including the extruded radiator shown in FIG. 4A;

FIG. 4C is an enlarged, cross-section of the circled portion in FIG. 4B;

FIG. 5A is a section of an extruded radiator of a second embodimentradiator taken along lines VC-VC in FIG. 5C;

FIG. 5B is a section of the circuit breaker shown in FIG. 2A includingbetween each bushing and each terminal pad a cross-section of the secondembodiment radiator including the extruded radiator shown in FIG. 5A;

FIG. 5C is an enlarged cross-section of the circled portion in FIG. 5B;

FIG. 6A is an alternate arrangement of the conductor and extensionsegment shown in FIGS. 4B, 4C, 5B, and 5C including one or more internalBelleville washers within each threaded coupling;

FIG. 6B is an alternate arrangement of conductor(s) and extrusionsegment(s) shown in FIGS. 4B, 4C, 5B, and 5C including one or moreexternal Belleville washers between each pair of adjacent segments; and

FIGS. 7A and 7B are isolated, cross-sectional views of the bushings,terminal pads and first and second embodiment radiators of FIGS. 4B and5B coupled to blocks representing generic electrical power distributionelements, such as, without limitation, a transformer or an insulatedbus.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described with reference to theaccompanying figures where like reference numbers correspond to like orsubstantially similar elements. Herein, reference numbers followed bythe suffix “-1” or “-2” are different instances of the elementrepresented by the main reference number without the suffix. Forexample, two separate instances of bushing 14 are denoted by referencenumbers 14-1 and 14-2.

With reference to FIG. 1, an exemplary three-phase, mechanically ganged,sulfur hexafluoride (SF₆) gas insulating circuit breaker system 2includes a plurality of circuit breakers 4. The number of circuitbreakers 4 of circuit breaker system 2 is dictated by the number ofelectrical phases to be switched and controlled. For example, theexemplary circuit breaker system 2 shown in FIG. 1 includes threecircuit breakers 4 for switching three phases of a three-phase ACdistribution system. However, the number of circuit breakers 4illustrated in FIG. 1 is not to be construed as limiting the invention.

With reference to FIG. 2A and with continuing reference to FIG. 1, eachcircuit breaker 4 includes a main enclosure 6 which houses aninterrupter 8 which is electrically isolated from main enclosure 6 byway of insulating standoffs 10 and 12. More specifically, main enclosure6 includes a body 7 (which houses interrupter 8 and standoffs 10 and 12)and a pair of extensions (or arms) 35-1 and 35-2 which extend from body7.

Each circuit breaker 4 also includes first and second insulatingbushings 14-1 and 14-2 having proximal ends 16-1 and 16-2 coupled todistal ends of extensions 35-1 and 35-2. Current transformers 20-1 and20-1 are mounted surrounding extensions 35-1 and 35-2 between insulatingbushings 14-1 and 14-2 and body 7. Transformer housings 18-1 and 18-2surround transformers 20-1 and 20-1 and aid in protecting transformers20-1 and 20-1 from environmental conditions.

First and second conductors 22-1 and 22-2 are disposed inside of firstand second bushings 14-1 and 14-2 and inside of extensions 35-1 and35-2. Proximal ends 21-1 and 21-2 of first and second conductors 22-1and 22-2 are coupled to first and second contacts 24-1 and 24-2 ofinterrupter 8 defining a conductive path for current to flow betweenfirst and second contacts 24-1 and 24-2 and first and second conductors22-1 and 22-2, respectively.

Circuit breaker 4 also includes first and second terminal pads 26-1 and26-2 coupled between distal ends 19-1 and 19-2 of first and secondbushings 14-1 and 14-2 and distal ends 23-1 and 23-2 of first and secondconductors 22-1 and 22-2 disposed inside of first and second bushings14-1 and 14-2, respectively.

With reference to FIG. 2B and with continuing reference to FIGS. 1 and2A, interrupter 2 is switchable via electrical and/or mechanical modulesdisposed in a housing 28 between the closed state shown in FIG. 2A wherethe first and second contacts 24-1 and 24-2 of interrupter 8 areelectrically connected defining a conductive path for current to flowbetween the first and second contacts 24-1 and 24-2, and the open stateshown in FIG. 2B where the first and second contacts 24-1 and 24-2 areelectrically isolated from each other, and vice versa.

Each transformer 20 is positioned and configured to output an AC currentcorresponding to the AC current flowing in the corresponding conductor22. The current output by each transformer 20 facilitates monitoring theoperational status of circuit breaker 4 and invoicing for electricalpower (KVA) provided via circuit breaker 4.

As can be seen in FIGS. 2A and 2B, the insides of bushings 14-1 and 14-2include cavities 30-1 and 30-2 defined by interior walls 32-1 and 32-2of bushings 14-1 and 14-2. Portions or sections of conductors 22-1 and22-2 are disposed in cavities 30-1 and 30-2 in spaced relation tointerior walls 32-1 and 32-2 of bushings 14-1 and 14-2, respectively.The insides of extensions 35-1 and 35-2 also define internal cavities34-1 and 34-2 with portions or sections of conductors 22-1 and 22-2disposed in cavities 34-1 and 34-2 in spaced relation to interior wallsof extensions 35-1 and 35-2.

In use, interrupter 8 and first and second conductors 22-1 and 22-2 areexposed to an suitable electrically insulating fluid, such as, withoutlimitation, SF₆ gas, that is disposed in body 7 and cavities 30-1, 30-2,34-1, and 34-2.

Desirably, the electrically insulating fluid is sulfur hexafluoride(SF₆) which is an inert, non-toxic, odorless, non-flammable, andcolorless gas. Alternatively, the use of an electrically insulating oilis envisioned. SF₆ has excellent arc quenching properties and exhibitsexceptional thermal stability. SF₆ has exceptionally good insulatingproperties and, at atmospheric pressure, has 2.5 times the dielectricstrength of air. At a gas pressure of 289.6 kPa (42 psig), SF₆ gas has asame dielectric strength as transformer oil.

SF₆ remains a gas without liquefying down to −34.4° C. (−30° F.) at gaspressures normally utilized in circuit breaker 4. The density of SF₆ isabout five times that of air and heat transfer by free convection is 1.6times that of air at atmospheric pressure and 2.5 times the value of airat 206.8 kPa (30 psig).

Arcing, which occurs during normal operation of circuit breaker 4, doesnot materially affect the insulating properties of the SF₆ gas. Thesolid arc decomposition products, observed as a fine grey powder, haveequally good dielectric properties.

Housing 28 houses suitable and/or desirable electrical, mechanical,and/or software modules that facilitate the switching of interrupter 8between the closed state shown in FIG. 2A and the open state shown inFIG. 2B, and vice versa. Housing 28 may also include suitableelectrical, mechanical, and/or software modules for detecting andprocessing the voltage and/or current output by each transformer 20-1and 20-2 and for forwarding an indication of said detected voltageand/or current to suitable processing means located remotely. Furtherdetails regarding the electrical, mechanical, and/or software modulesincluded in housing 28 will not be discussed herein for the purpose ofsimplicity.

In operation of circuit breaker 4, terminal pads 26-1 and 26-2 arecoupled to lines (not shown) of a single phase of an AC distributionsystem. In use, as electrical current flows through first terminal pad26-1, first conductor 22-1, interrupter 8 in its closed state, secondconductor 22-2, and second terminal pad 26-2, the temperature of the SF₆gas enclosed inside of enclosure 6, housings 18-1 and 18-2, and bushings14-1 and 14-2 increases. The warm SF₆ gas tends to rise and stagnate atthe highest point, which is usually just below terminal pads 26-1 and26-2 at the top of bushings 14-1 and 14-2.

With reference to FIGS. 3A-3C and with continuing reference to FIGS.1-2B, heretofore, as an aid to dissipating the heat in the SF₆ gasstagnating at the top of each bushing 14, a radiator 136 was disposedbetween the distal end 19 of the bushing 14 and the correspondingterminal pad 26. Radiator 136 included a tube 138 and a plurality ofseparately formed elongated fins 140 that are disposed (welded) aroundthe exterior surface of tube 138. In the embodiment of radiator 136shown in FIGS. 3A-3C, the longitudinal axis of each fin 140 extendsparallel or substantially parallel to a central axis 142 of tube 138. InFIG. 3A, the central, longitudinal axis 142 of tube 138 extends normal(into) the surface of the page.

Each fin 140 is generally hexahedron-shaped (e.g., a right rectangularprism) having substantially planar sides and, desirably, the square orrectangular cross-section shown in FIGS. 3A-3B. As a result of thisarrangement, each fin 140 had one planar side 144 that is mated with thecurved exterior surface of tube 138 during the manufacturing of radiator136 (see especially FIG. 3B). As can be understood from FIG. 3B, whenthe planar side 144 of a fin 140 is mated to the curved exterior surfaceof tube 138, one or more welds 148 and, possibly one or more gaps 146,will be present between planar side 144 and the curved exterior surfaceof tube 138. As would be readily understood, each such weld 148 and anygap 146 represents a discontinuity for the flow of heat between tube 138and fin 140.

Interface plates or brackets (not shown) are utilized to couple the topend (shown in FIG. 3A) of radiator 136 to terminal pad 26 and to couplethe bottom end (not shown in any of the figures) of radiator 136 to thedistal end 19 of bushing 14. Additional details regarding radiator 136shown in FIGS. 3A-3C and the coupling thereof between the distal end 19of bushing 14 and the corresponding terminal pad 26 are not describedherein for the purpose of simplicity.

The additional distance created between the distal end 19 of bushing 14and the corresponding terminal pad 26 resulting from the addition ofradiator 136 therebetween was accounted for by either increasing thelength of conductor 22 or by adding an additional length of conductivesegment (not shown in FIGS. 2A-3C) to either end of conductor 22.

Having thus described the current solution, first and second embodimentsof the present invention will now be described.

With reference to FIGS. 4A-4C, an instance of a first embodimentradiator 36 that can be disposed between the distal end 19 of eachbushing 14 and the corresponding terminal pad 26 includes an extrudedradiator 37 that includes a central tube segment or portion 38 and aplurality of radially extending, elongated fin segments or portions 40integral with the exterior of tube segment 38. Desirably, thelongitudinal axis of each fin segment 40 extends parallel orsubstantially parallel to a central axis 42 of tube segment 38. In FIG.4A, the central, longitudinal axis 42 of tube segment 38 extends normalto (into) the surface of the page.

As shown best in FIG. 4A, the transition between tube segment 38 andeach fin segment 40 is a smooth transition without gaps or welds, andthe tip or end of each fin segment 40 is rounded. The absence of anygaps or welds between tube segment 38 and each fin segment 40facilitates heat flow from the interior cavity 39 of tube segment 38 toeach fin segment 40. Moreover, the rounded tip or end of each finsegment 40 facilitates uniform heat dissipation by avoiding the sharpedges of the fins 140 of the radiator 136 discussed above in connectionwith FIGS. 3A-3C.

With ongoing reference to FIGS. 4A-4C, each instance of first embodimentradiator 36 also includes a top plate 48 and a bottom plate 50 which arecoupled to an interior surface of tube segment 38 at the top and bottomof tube segment 38. More specifically, the outside perimeter of topplate 48 is affixed to the interior surface of tube segment 38 at thetop side of tube segment 38 via a weld 52. Similarly, the outsideperimeter of bottom plate 50 is affixed to the interior surface of tubesegment 38 at the bottom of tube segment 38 via a weld 54. Welds 52 and54 desirably extend around the perimeter of top plate 48 and bottomplate 50, respectively.

A stub segment 56 secured to the bottom surface of top plate 48 via aweld 58 extends into the interior cavity 39 of tube segment 38. Stubsegment 56 is coupled to the distal end 23 of conductor 22, whichextends into the interior of tube segment 38 through a central openingin bottom plate 50, via a threaded coupling 64. As shown in FIGS. 4B and4C, an extension segment 60 is coupled between the proximal end 21 ofconductor 22 and contact 24. More specifically, one end of extensionsegment 60 is coupled to the proximal end 21 of a conductor 22 via athreaded coupling 66 and the other end of extension segment 60 iscoupled to a contact 24 of interrupter 8 in a manner known in the art.

In FIG. 4C, threaded coupling 64 includes a male threaded segment ofconductor 22 threadedly mated with a female threaded opening of stubsegment 56. Threaded coupling 66 includes a female threaded opening ofconductor 22 threadedly mated with a male threaded segment of extensionsegment 60. However, the particular arrangement of male threadedsegments and female threaded openings comprising threaded couplings 64and/or 66 is not to be construed as limiting the invention as it isenvisioned that any suitable and/or desirable means of coupling the ends23 and 21 of conductor 22 to stub segment 56 and extension segment 60can be utilized. It is envisioned that the use of extension segment 60with extruded radiator 37 is optional inasmuch as it is envisioned that,alternatively, the length of conductor 22 can be increased to accountfor the addition of extruded radiator 37 to the distal end 19 of bushing14.

To facilitate the coupling of bottom plate 50 to the distal end 19 ofbushing 14, a flange 68 is provided (welded) around the exterior ofbushing 14 adjacent the distal end 19 of bushing 14. Flange 68 includesa pattern of through-holes 70 and bottom plate 50 includes acorresponding pattern of threaded holes 72 that are configured to bealigned with each other in use. At a suitable time after eachthrough-hole 70 and a corresponding threaded hole 72 are aligned, themale threads of a threaded bolt 74 can be mated with the female threadsof threaded hole 72 via through-hole 70 to secure bottom plate 50 toflange 68 and, hence, to the distal end 19 of bushing 14.

To avoid the escape of SF₆ gas at the point where bottom plate 50 iscoupled to bushing 14, an O-ring 76 can be disposed in an annular groove78 in the portion of the bottom surface of bottom plate 50 that comesinto contact with the distal end 19 of bushing 14. When bottom plate 50is secured to flange 68 via the threaded ends of bolts 74 threadedlyreceived in through-holes 70 and threaded holes 72, O-ring 76 in annulargroove 78 is compressed thereby avoiding the escape of SF₆ gas betweenthe portion of the bottom surface of bottom plate 50 in contact with thedistal end 19 of bushing 14. In FIG. 4C annular groove 78 is illustratedas being formed in bottom plate 50. However, this is not to be construedas limiting the invention since it is envisioned that annular groove 78can be formed in the distal end 19 of bushing 14.

Desirably, extruded radiator 37 (including tube segment 38 and fins 40),top plate 48, bottom plate 50, and stub segment 56 are all made from thesame material, e.g., aluminum, and extension segment 60 is made fromanother material, e.g., copper. However, this is not to be construed aslimiting the invention. Also, as discussed above, each bushing 14 isformed from an insulating material, such as a ceramic, a compositematerial, or any other suitable and/or desirable insulating material.Furthermore, terminal pad 26 can also be made from a conductive materialsuch as, without limitation, aluminum.

When an instance of first embodiment radiator 36 is utilized, terminalpad 26 can be welded to top plate 48 via a weld 79 as shown in FIG. 4C.However, this is not to be construed as limiting since it is envisionedthat terminal pad 26 can be coupled to top plate 48 in any suitableand/or desirable manner.

With reference to FIGS. 5A-5C, an instance of a second embodimentradiator 80 that can be disposed between the distal end of each bushing14 and the corresponding terminal pad 26 is an extruded radiator 82 thatincludes a tube segment or portion 84 and a plurality of radiallyextending, elongated fin segments or portions 86 integral with theexterior of tube segment 84. Desirably, the longitudinal axis of eachfin segment 86 extends parallel or substantially parallel to a centralaxis 88 of extruded radiator 82. In FIG. 5A, the central, longitudinalaxis of extruded radiator 82 extends normal to (into) the surface of thepage.

As shown best in FIG. 5A, the transition between tube segment 84 andeach fin segment 86 is a smooth transition without gaps or welds, andthe tip or end of each fin segment 86 is rounded. The absence of anygaps or welds between tube segment 84 and each fin segment 86facilitates heat flow from the interior cavity 85 of extruded radiator82 to each fin segment 86. Moreover, the rounded tip or end of each finsegment 86 facilitates heat dissipation by avoiding the sharp edges ofthe fins 140 of radiator 136 discussed above in connection with FIGS.3A-3C.

As can be seen by comparing FIGS. 4B and 5B, an instance of secondembodiment radiator 80 can be used in place of an instance of firstembodiment radiator 36 on the distal end 19 of a bushing 14. It is to beappreciated that the circuit breakers 4 shown in FIGS. 2A, 2B, 4B, and5B are the same except for the alternate use of instances of the firstand second embodiment radiators 36 and 80 for radiator 136 and theaddition of an instance of extension segment 60 as a bridge between eachcontact 24 and the proximal end 21 of a conductor 22, which wouldnormally be coupled together in the circuit breaker 4 shown in FIGS. 2Aand 2B, but which are separated (or spaced apart) by the addition offirst or second embodiment radiator 36 or 80 between bushing 14 and topplate 26 shown in FIGS. 4B and 5B.

With ongoing reference to FIG. 5C, a subset (all or less than all) ofthe fin segment(s) 86 of an instance of extruded radiator 82 can includethreaded holes 88 and 90 at opposite ends of said fin segment 86. Thepattern of threaded holes 90 of the fin segments 86 of extruded radiator82 correspond to the pattern of through-holes 70 of flange 68 whereuponthe pattern of through-holes 70 and the pattern of threaded holes 90 canbe aligned with each other in use. Each threaded hole 90 is configuredto threadedly receive the threaded end of a bolt 74 via one of thethrough-holes 70 in flange 68.

A terminal pad 26 that includes a pattern of through-holes 92corresponding to the pattern of threaded holes 88 in the fin segments 86of extruded radiator 82 can be coupled to an end of extruded radiator 82opposite flange 68 via the threaded ends of bolts 94 engaging threadedholes 88 via through-holes 92 in terminal pad 26.

To avoid the escape of SF₆ gas at the points where the top of extrudedradiator 82 is coupled to terminal pad 26 and the bottom of extrudedradiator 82 is coupled to bushing 14, O-rings 96 and 98 can bepositioned in annular grooves 100 and 102. In FIG. 5C, annular grooves100 and 102 are illustrated as being formed in the side of terminal pad26 that is coupled to the top of extruded radiator 82 and in the end oftube segment 84 that contacts the distal end 19 of bushing 14. However,this is not to be construed as limiting the invention since it isenvisioned that annular groove 100 can be formed in the end of tubesegment 84 to be covered by terminal pad 26 and/or annular groove 102can be formed in the distal end 19 of bushing 14.

As can be seen, the use of an instance of first embodiment radiator 36or an instance of second embodiment radiator 80 between the distal end19 of a bushing 14 and a terminal pad 26 facilitates the transfer ofheat from the otherwise stagnant gas trapped inside cavities 39 and 85of tube portions 38 and 84, respectively, and/or cavity 30 of bushing14.

As can be seen in FIG. 4A, the fin segments 40 of extruded radiator 37are integrally formed with tube segment 38, i.e., without any gaps orwelds between each fin segment 40 and tube segment 38. Similarly, asshown in FIG. 5A, the fin segments 86 of extruded radiator 82 areintegrally formed with tube segment 84, i.e., without any gaps or weldsbetween each fin segment 86 and tube segment 84. By way of thisarrangement, the heat flow discontinuity that results from gaps 146 andwelds 148 between fin segments 140 and the curved or rounded exterior oftube 138 of radiator 136, shown in FIGS. 3A-3C, is avoided.

Referring back to FIGS. 4C and 5C, each threaded coupling 64 and 66 caninclude one or more internal Belleville washers 104 (or one or morecoiled springs) between the base of the female threaded opening and thetip of the male threaded segment. Desirably, at least one of the malethreads and the female threads of each threaded coupling 64 and 66 isplated with a suitable conductive material, such as silver, copper, ortin, that facilitates good electrical contact therebetween, especiallyunder conditions where one or both of threaded couplings 64 and/or 66 issubject to extreme temperature variations normally attendant with theuse of circuit breaker 4. When a threaded coupling 64 or 66 includes twoor more Belleville washers 104, said Belleville washers 104 can beconnected in series, in parallel, or in some combination of series andparallel as deemed suitable and/or desirable.

The one or more internal Belleville washers 104 (or one or more coiledsprings) of each threaded coupling 64 and 66 act as a biasing means orbiasing element that aids in maintaining the male threads and the femalethreads of each threaded coupling 64 and 66 in contact. The internalBelleville washers 104 (or coiled springs) associated with threadedcoupling 66 also act to spring bias conductor 22 toward top plate 48 andto spring bias extension segment 60 toward contact 24. Similarly, theone or more internal Belleville washers 104 (or coiled springs)associated with threaded coupling 64 also act to spring bias conductor22 toward contact 24.

While FIGS. 4C and 5C specifically illustrate one or more internalBellville washers 104 associated with threaded coupling 64 and one ormore internal Belleville washers 104 associated with threaded coupling66, this is not to be construed as limiting the invention since it isenvisioned that only a single set of one or more internal Bellevillewashers 104 (or one or more coiled springs) can be provided withthreaded coupling 64 or threaded coupling 66, whereupon no Bellevillewashers 104 would be associated with the other threaded coupling. Inthis regard, it is envisioned that the use of one or more internalBelleville washers 104 (or one or more coiled springs) with threadedcoupling 64 in combination one or more internal Belleville washers 104(or one or more coiled springs) with threaded coupling 66 may beredundant.

With reference to FIG. 6A, and with reference back to FIGS. 4A-5C, it isenvisioned that the position of extension segment 60 between contact 24and stub segment 56 can be changed whereupon extension segment 60 iscoupled between the distal end 23 of conductor 22 and stub segment 56via threaded couplings 64 and 66 while the proximal end 21 of conductor22 is coupled directly to contact 24 in a manner known in the art.

With reference to FIG. 6B, also or alternatively, it is envisioned thatthree or more conductive segments 106, 108, and 110 can be coupledbetween stub segment 56 and contact 24 via threaded couplings 112, 114,and 116, each of which includes one or more external Belleville washers118 (or one or more coiled springs), with the external Bellevillewashers 118 connected in series, in parallel, or in some combination ofseries and parallel, between each pair of adjacent segments 106, 108,110, and 56 surrounding the shaft of the male threaded segment of eachthreaded coupling 112, 114, and 116.

In the embodiment shown in FIG. 6B, one or more of the conductivesegments 106, 108, and 110 can be formed from aluminum and one or moreof the conductive segments 106, 108, 110 can be formed from copper (likeextension segment 60 in FIGS. 4C, 5C, and 6A). For example, any one ofsegments 106, 108, and 110 can be formed from copper, and the othersegments can be formed from aluminum. Where a threaded coupling 112,114, or 116 includes male or female threads made of copper, and matingfemale or male threads made of aluminum, one or both of the male andfemale threads of said threaded coupling can be silver, copper, or tinplated to facilitate good electrical connection therebetween.

Desirably, the internal Belleville washers 104 shown in FIGS. 4C, SC,and 6A are used since, in practice, a majority of electrical currentpasses along the exterior surfaces of the conductors, contacts, orconductive segments (22, 24, 56, and 60) being coupled together.However, the use of external Belleville washers 118 shown in FIG. 6B isa viable alternative to the use of internal Belleville washers 104.Moreover, the mixed use of internal Belleville washers 104 and externalBelleville washers 118 is envisioned. For example, without limitation,one threaded coupling 64 or 66 in FIGS. 4C and 5C can include internalBelleville washers 104 while the other threaded coupling 66 or 64 canuse external Belleville washers 118.

The invention has been described with reference to the accompanyingfigures. Obvious modifications and alterations will occur to others uponreading and understanding the preceding detailed description. Forexample, each set of (one or more) Belleville washers can be replacedwith one or more coiled spring. Moreover, as shown in FIGS. 7A and 7B,each embodiment extruded radiator 36 and 80 can be utilized on thedistal end of an insulating bushing (e.g., without limitation, likeinsulating bushing 14) that is coupled at its proximal end to a contact122 a different type (different than circuit breaker 4 discussed above)of power distribution element 120, such as an oil or SF₆ filledtransformer, or an oil or SF₆ filled insulated bus, versus the mainenclosure 6 shown herein. It is intended that the invention be construedas including all such modifications and alterations insofar as they comewithin the scope of the appended claims or the equivalents thereof.

1. (canceled)
 2. The circuit breaker of claim 6, wherein including firstand second radiators coupled between the distal ends of the first andsecond bushings and the first and second terminal pads, respectively,wherein at least a portion of the first or second segment of the oneconductor is disposed inside one of the radiators
 3. The circuit breakerof claim 6, wherein the second ends of the first and second segments arecoupled together via male threads of one segment threadedly engaged infemale threads of the other segment.
 4. The circuit breaker of claim 3,wherein one segment is made from aluminum; the other segment is madefrom copper; and at least one of the male threads and the female threadsis silver, copper, or tin plated.
 5. The circuit breaker of claim 6,wherein: the first end of the first segment is coupled directly to thecontact of the interrupter; and the first end of the second segment iscoupled directly to the one terminal pad.
 6. A circuit breaker designedfor use with AC voltages greater than 30 kilovolts and AC currentsgreater than 400 amperes, the circuit breaker comprising: a mainenclosure housing an interrupter that is electrically insulated from themain enclosure, wherein the interrupter is switchable between a closedstate where first and second contacts of the interrupter areelectrically connected defining a conductive path for current to flowbetween the first and second contacts and an open state where the firstand second contacts of the interrupter are electrically isolated fromeach other, and vice versa; first and second electrically insulatingbushings having proximal ends coupled to the main enclosure; first andsecond conductors disposed inside of the first and second bushings,wherein proximal ends of the first and second conductors areelectrically connected to the first and second contacts of theinterrupter defining a conductive path for current to flow between thefirst and second contacts and the first and second conductors,respectively; and first and second terminal pads coupled between distalends of the first and second bushings and distal ends of the first andsecond conductors disposed inside of the first and second bushings,respectively, wherein: at least one conductor includes first and secondsegments; a first end of the first segment is electrically connected toone of the contacts of the interrupter; a first end of the secondsegment is electrically connected to one of the terminal pads; a secondend of the first segment is coupled to a second end of the secondsegment and a biasing element is interposed between the second ends ofthe first and second segments, wherein the biasing element is operativefor biasing the first end of the first segment toward the contact of theinterrupter and for biasing the first end of the second segment towardthe one terminal pad, wherein the biasing element includes a Bellevillewasher (a coned-disc spring, a conical spring washer, a disc spring, aBelleville spring, or a cupped spring washer) or a coiled spring.
 7. Thecircuit breaker of claim 6, wherein the biasing element includes a pairof Belleville washers connected in series or in parallel.
 8. The circuitbreaker of claim 6, wherein the at least one conductor further includesa third segment coupled with the first segment, with the second segment,or with both of the first and second segments.
 9. (canceled)
 10. Thecircuit breaker, or transformer, or insulated bus of claim 14, furtherincluding an elongated radiator disposed between the second end of thebushing and the terminal pad, wherein at least a portion of the first orsecond segment of the conductor is disposed inside of the radiator. 11.The circuit breaker, or transformer, or insulated bus of claim 14,wherein the second ends of the first and second segments are coupledtogether via male threads of one segment threadedly engaged in femalethreads of the other segment.
 12. The circuit breaker, or transformer,or insulated bus of claim 11, wherein one segment is made from aluminum;the other segment is made from copper; and at least one of the malethreads and the female threads is silver, copper, or tin plated.
 13. Thecircuit breaker, or transformer, or insulated bus of claim 14, wherein:the first end of the first segment is coupled directly to the contact;and the first end of the second segment is coupled directly to the oneterminal pad.
 14. A circuit breaker, or transformer, or insulated busdesigned for use with AC voltages greater than 30 kilovolts and ACcurrents greater than 400 amperes, the circuit breaker, or transformer,or insulated bus comprising: an elongated bushing made from electricallyinsulating material and having first and second ends, the first end ofthe bushing coupled to a main enclosure; a terminal pad coupled to thesecond end of the bushing; and a conductor disposed in an internalcavity of the bushing in spaced relation to an internal wall of thebushing that defines the internal cavity, wherein: the conductorincludes first and second segments; a first end of the first segment iselectrically connected to a contact; a first end of the second segmentis electrically connected to the terminal pad; a second end of the firstsegment is coupled to a second end of the second segment and a biasingelement is interposed between the second ends of the first and secondsegments, wherein the biasing element is operative for biasing the firstend of the first segment toward the contact and for biasing the firstend of the second segment toward the terminal pad, wherein the biasingelement includes a Belleville washer (a coned-disc spring, a conicalspring washer, a disc spring, a Belleville spring, or a cupped springwasher) or a coiled spring.
 15. The circuit breaker, or transformer, orinsulated bus of claim 14, wherein the biasing element includes a pairof Belleville washers connected in series or in parallel.
 16. Thecircuit breaker, or transformer, or insulated bus of claim 14, whereinthe conductor further includes a third segment coupled with the firstsegment, with the second segment, or with both of the first and secondsegments.